In the States these are called Mighty Muggs. There is an online store where you can buy blank ones, just in case you feel bad about painting over a potential collector item. The blanks are about the same price as a themed one.

You and Atomictonytiki haven't been alone in this idea... I wonder if this is some sort of Close Encounters of the Third Kind situation where we have to paint these things, or our versions of them, to get them out of our heads... only to find out we are being lead to some giant Munny/Mighty Muggs doll that we must worship? I guess as long as Mai Tais are involved, I'll go with it.

I learn something new every day I had seen those before but didn't know what they were.

From Wikipedia:
Custom Mighty Muggs - There exists a large community of toy enthusiasts whose ambition is to customize toys. Though this is not a new phenomena, each new toy line does present new challenges and opportunities for expression. Mighty Muggs are no exception. The form is simple, humanoid, and the surface is smooth, rounded.

There are a number of accessories that have been produced, available only with certain figures, each of which offers exponential customizing options to a savvy customizer. examples: a helmet can be turned into a hairpiece, or a light saber can be whittled into a sword.

Still more options are available once putties or modeling clays are introduced, such as "Mighty Putty", "Apoxie® Sculpt", or "Sculpti". With these modeling compounds artists have transformed flat surfaces into three dimensional eyebrows, hair, horns, tails, etc.

Often found objects, or parts of other toys are used to lend a more realistic or dynamic appearance to the figure. examples include: feathers for wings, or weapons from another toy figurine, or LED lights for lighting effects.

Still, the most prolific form of customization seems to be a good old-fashioned re-paint. The Mighty Mugg's surface is a nearly perfect ground for creating an image with paint, due to it's factory smooth paintjob and lack of protruding features

Hey TR, my wife and I passed by our local URBAN OUTFITTERS store, where they have Tons of the prepainted Mighty Mugs of various MArvel and DC characters. BUT, to my surprise, they have a large amount of these Blank versions on clearance for 4.99 each. I was only able to buy one right now, but I'd like to go and buy several more so that when I'm ready to give painting them a go...I'll have a bunch I can use.

Spot on - The only blanks I could find were on ebay and lots of money once delivered. I found my muggs on play.com [a uk website], they were the unpopular Mutt from Indi 4. Mine were 4.99 pounds delivered.